14 shorter answers to get clear on some concepts 23 sentence

14. (shorter answers- to get clear on some concepts): (2-3 sentence max, each)*

c) name and briefly describe function for thyrotropin, a gonadotropin, corticotropin

d) Consider the hormone oxytocin. Describe its source, target and effects, then describe the type of control mechanism involved. Describe two stimuli for oxytocin’s release (*maybe 5-6 sentences here)321

e) Oxytocin and ADH can be accurately described as from the hypothalamus or from the pituitary. Briefly explain why either description is correct.

f) Occasionally, a woman who has not recently been pregnant is found to be producing and releasing breast milk. More rarely, a man may be doing this. This can be caused by a particular tumor which would be releasing what hormone? Describe its normal source and target.

Solution

c). The thyrotropin is a tropic hormone released by the anterior pituitary, which acts on thyroid gland to release the thyroid hormones. Similarly, the gonadotropin stimulate the gonads and are necessary for fertility. Corticotropin released by the anterior pituitary acts on adrenal cortex to release the adrenocortical hormones.

d). The oxytocin is synthesized by the hypothalamus and is released by the posterior pituitary. Its release is regulated by the positive feedback mechanism. Release of oxytocin during labour pains is the best example of positive feedback regulation. In this, the initial release of oxytocin triggers uterine contraction.

The two stimuli that cause release of oxytocin are, suckling of nipples by the baby and the stretch if uterus by prostaglandins during labor.

e). The hypothalamus produces two endocrine hormones, oxytocin and vasopressin (anti diuretic hormone (ADH)). These hormones are released from the posterior pituitary.

The neurohypophysis constitute the neural part of the pituitary gland. As it is descended from the brain, the posterior pituitary hormones are actually produced by the paraventricular nuclei and the supraoptic nuclei of the hypothalamus. The release of vasopressin and the oxytocin from the neurohypophysis are regulated by neuroendocrine reflexes.